Electrical contact elements



United States Patent ELECTRICAL CONTACT ELEIVIENTS 2,830,898 Patented Apr. 15, 1958 added to silver and/or copper base compositions. More particularly, the contact element compositions according to this invention are formed of 1% to 25% of cadmium oxide particles dispersed in an alloy consisting essentially 5 of 0.25% to 15% of a modifying agent and the remainder Childress B. Gwyn, Jr., North Attleboro, Mass., assignor 3 1116181 t d fr the gr p Consisting of Silver n to Metals & Controls Corporation, Attleboro, Mass., a copper, all of these percentages being by weight of the corporation of Massachusefls whole. The modifying agent of these compositions con- N Drawing Application October 4,1956 sists essentially of a material selected from the group Serial 613,837 conslsting of hafmum, vanadium and zirconlum and mixtures thereof.

5 Claims- The efficacy of the contact element compositions of this invention are demonstrated, in part, by the following table. Although this tables does not include a composi- This invention relates to electrical contact elements, tion in which the modifying agent consisted essentially and more particularly to. electrical contact elements of vanadium or a mixture of two or all three of hafnium, formed of improved compositions. vanadium and zirconium (within the above stated range),

An object of this invention is to provide electrical conit has been found that these compositions provide subtact elements formed of improved compositions. A furstantially the same unexpectedly good results. It will be ther object of this invention is to provide such contact understood that in the table below, each of the composielements which exhibit less inherent electrical resistance tions identified by the respective modifying agents and rise and which resist tarnishing due to the circumambient their percentages consists essentially of 10% cadmium atmospheres in which these contact elements are ordioxide particles dispersed in an alloy consisting essentially narily disposed. of the stated percentage of modifying agent and the re- A further object of this invention is to provide elecmainder silver, all by weight of the whole. It will further trical contact elements formed of silver-base or copperbe understood that the first figure in each of the columns base compositions, each of which includes cadmium oxide of the table below represents the test results for a comand minor percentages of a modifying agent, which modiposition which consisted essentially of 10% by weight of fying agent so affects the resulting composition that unexcadmium oxide particles dispersed in silver without any pectedly beneficial characteristics are exhibited thereby. modifying agent. To obtain these test results, two of the A further object of this invention is to provide elecrespective cooperating contact elements, both of which trical contact elements formed of improved compositions, were formed of the stated composition, were operated which contact elements are economical and reliable in through 10,000 make and break cycles and the resulting operation, increase in voltage drop across these cooperating contact Other objects will be in part obvious and in part pointed elements was determined. This determination was accomout hereinafter. plished by measuring, both before and after the 10,000

The invention accordingly comprises the elements, make and break cycles, the millivolt drop across these combinations of elements, the ingredients, combinations respective. two contact elements when closed under a of ingredients, the proportions thereof, and features of pressure of 30 grams and while 10 amperes of direct composition which will be exemplified in the products 40 current flowed therethrough. The figures listed under hereinafter described, and the scope of the application of A are the average millivolt drop across the respective which will be indicated in the following claims. pairs of contact elements before the 10,000 cycles, and

The efficacy of silver-cadmium oxide and copper-cadunder B the average millivolt drop across the same mium oxide as contact element compositions is well pairs of contact elements after the 10,000 cycles. In known in the art. The advantageous operational characthis table, X indicates that the circuit remained open teristics of contact elements formed of such compositions after 1100 making and breaking cycles, XX indicates have been more or less limited heretofore to applications that the circuit remained open after 2980 making and in which the voltage across and the current through the breaking cycles, and XXX indicated that the operation contact elements were of comparatively high magnitude. of the respective contact elements became so erratic after When the voltage across such electrical contact elements 5100 making and breaking cycles as to render the contact is comparatively low, regardless of whether the current elements unfit for operation.

1 ampere, 1 ampere, 1 ampere, 1 ampere, 10 amperes, 25 amperes, 2 volts D. O. 6 volts D. C. 12 volts A. O 120 volts A. O. 120 volts A. C. 230 volts A. C.

Modifying Agent A B A B A B A B A B A B X 73 XX 71 XXX 73 130 73 170 73 155 70 70 102 70 100 70 97 70 109 70 110 71 97 71 97 71 89 71 104 71 11s 71 112 71 99 71 99 71 97 71 99 71 109 71 102 therethrough is comparatively low or high, the capability In the above table it will be noted that whereas the of such contacts to resist electrical surface resistance rise silver-cadmium oxide contacts went open circuit after only is deleteriously affected. For example, silver-cadmium 1100 making and breaking cycles at l ampere, 2 volts, oxide contact elements ordinarily function satisfactorily at (35 direct current, such did not occur with the improved volts, 15 amperes, alternating or direct current. electrical contact elements of this invention. Also, as However, such contact elements do not function equally 1 ampere, 6 volts, direct current and at 1 ampere, 12 well at 6 volts, 15 amperes, are extremely erratic at 1 or volts, alternating current, the circuit remained open after 2 volts, 15 amperes, and are also extremely erratic at 1 or substantially less than 10,000 make and break cycles. 2 volts and currents of less than 1 ampere. 70 Furthermore, even in the comparatively moderate current According to this invention, minor percentages of hafnium, vanadium or Zirconium or mixtures thereof are and voltage ranges such as 10 amperes, 120 volts, alternating current and 25 amperes, 230 volts, alternating current, the resistance drop across the contacts as a result of 10,000 make and break cycles was substantially less with the contact element compositions of this invention.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

I claim:

1. An electrical contact element formed of 1% to 25% of cadmium oxide particles dispersed in an alloy consisting essentially of 0.25% to 15% of a modifying agent and the remainder selected from the group consisting of silver and copper, said modifying agent being selected from the group consisting of hafnium, vanadium and zirconium and mixtures thereof, and said percentages being by weight of the Whole.

2. An electrical contact element formed of 1% to 25% of cadmium oxide particles dispersed in an alloy consisting essentially of 0.25 to 15% of hafnium as a modifying agent and the remainder selected from the group consisting of silver and copper, said percentages being by weight of the whole.

3. An electrical contact element formed of 1% to 25% of cadmium oxide particles dispersed in an alloy consist- 4. ing essentially of 0.25% to 15% of zirconium as a modifying agent and the remainder selected from the group consisting of silver and copper, said percentages being by weight of the whole.

4. An electrical contact element formed of 1% to 25 of cadmium oxide particles dispersed in an alloy consisting essentially of 0.25% to 15 of vanadium as a modifying agent and the remainder selected from the group consisting of silver and copper, said percentages being by weight of the whole.

5. An electrical contact element formed of 1% to 25 of cadmium oxide particles dispersed in an alloy consisting essentially of 0.25% to 15 of a mixture of at least two of hafnium, vanadium and zirconium as a modifying agent and the remainder selected from the group consisting of silver and copper, said percentages being by weight of the whole.

References Cited in the file of this patent UNITED STATES PATENTS 2,145,690 Hensel Ian. 31, 1939 2,180,984 Hensel Nov. 21, 1939 2,545,438 Stumbock Mar. 20, 1951 

1. AN ELECTRICAL CONTACT ELEMENT FORMED OF 1% TO 25% OF CADMIUM OXIDE PARTICLES DISPERSED IN AN ALLOY CONSISTING ESSENTIALLY OF 0.25% TO 15% OF A MODIFYING AGENT AND THE REMAINDER SELECTED FROM THE GROUP CONSISTING OF SILVER AND COPPER, SAID MODIFYING AGENT BEING SELECTED FROM THE GROUP CONSISTING OF HAFNIUM, VANADIUM AND ZIRCONIUM AND MIXTURES THEREOF, AND SAID PERCENTAGES BEING BY WEIGHT OF THE WOLE. 